The source of heme for vascular heme oxygenase II: de novo heme biosynthesis in rat aorta

2004 ◽  
Vol 82 (4) ◽  
pp. 218-224 ◽  
Author(s):  
Kinga Jaronczyk ◽  
Loc Bui ◽  
Jonathan M Soong ◽  
Brian E McLaughlin ◽  
Gerald S Marks ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Heme Oxygenase ◽  
De Novo ◽  
Aminolevulinic Acid ◽  
Soluble Guanylyl Cyclase ◽  
Rat Aorta ◽  
Heme Biosynthesis ◽  
Activity Levels ◽  
Sprague Dawley ◽  
Prosthetic Group

Heme is an essential prosthetic group or substrate for many proteins, including hemoglobin, and hemo enzymes such as nitric oxide synthase, soluble guanylyl cyclase, and heme oxygenase (HO). HO is responsible for the breakdown of heme into equimolar amounts of biliverdin, iron, and carbon monoxide, the latter of which is thought to play a role in the regulation of vascular tone. It is not clear whether the source of heme for cardiovascular functions is derived from uptake from the extracellular milieu or synthesis. In this study, we tested the hypothesis that blood vessels obtain their supply of heme for HO through de novo synthesis. Adult male Sprague–Dawley rat aorta was incubated at 37 °C in Krebs' solution with 1 µM [14C]δ-aminolevulinic acid (ALA). [14C]ALA uptake was linear for about 30 min and reached a plateau at approximately 100 min. The radioactivity was incorporated into porphyrins and heme as determined by esterification of 14C-labelled metabolites and thin-layer chromatography. The first and rate-limiting step of heme biosynthesis is catalyzed by ALA synthase (ALA-S), the activity of which was determined in rat aorta using a radiometric assay, ~250 nmol·(g wet mass)–1·h–1. Inducing HO-1 in rat aorta with S-nitroso-N-acetyl penicil la mine (500 µM) did not increase ALA-S activity as compared with basal activity levels of the enzyme. It appears that there is a sufficient amount of heme available under basal ALA-S activity conditions to meet the increased demand for heme resulting from HO-1 induction. These observations indicate that the complete enzymatic pathway for de novo heme biosynthesis resides in rat aorta and furthermore indicate that de novo heme synthesis is capable of supplying a substantial portion of the heme substrate for HO in the aorta.Key words: heme biosynthesis, vasculature, carbon monoxide, heme oxygenase, δ-aminolevulinic acid synthase.

The source of heme for vascular heme oxygenase I: heme uptake in rat aorta

2004 ◽  
Vol 82 (4) ◽  
pp. 209-217 ◽  
Author(s):  
Loc Bui ◽  
Kimberly Rish ◽  
Kinga Jaronczyk ◽  
Stephane Bourque ◽  
Brian E McLaughlin ◽  
...  
Keyword(s):  
Cardiovascular System ◽  
Heme Oxygenase ◽  
Plasma Proteins ◽  
De Novo ◽  
Soluble Guanylyl Cyclase ◽  
Rat Aorta ◽  
Aortic Tissue ◽  
Heme Uptake

During the last decade, heme oxygenase (HO) and carbon monoxide (CO) have garnered substantial research interest in terms of cell and organ regulation, especially as they bear on the central nervous system, organ transplantation, and the cardiovascular system. While the enzymatic mechanism, substrates, and products of HO are well known, it is not clear whether the cardiovascular system derives its supply of the heme substrate through de novo synthesis or uptake from the extracellular milieu. The objective of the present study was to test the latter possibility in rat aorta and to determine the influence of plasma proteins that bind heme in vivo, viz. hemopexin and albumin. Aortic tissue was exposed to [14C]heme in vitro, and the concentration and time dependence of heme uptake was assessed. The presence of hemopexin or albumin in the incubation medium dramatically decreased heme uptake by the aorta. Heme uptake by aortic tissue was not altered after induction of HO-1, which would be expected to increase tissue heme demand. In summary, the rat, isolated aorta was capable of obtaining heme from its external milieu, but this was obtunded in the presence of the plasma proteins hemopexin or albumin. For normal physiological situations, heme uptake may not be a usual source of substrate for vascular HO and hemoenzymes such as nitric oxide synthase, soluble guanylyl cyclase, and cyclooxygenase.Key words: heme uptake, vasculature, heme oxygenase, hemopexin.

Carbon monoxide promotes endothelium-dependent constriction of isolated gracilis muscle arterioles

2003 ◽  
Vol 285 (3) ◽  
pp. R536-R541 ◽  
Author(s):  
Fruzsina K. Johnson ◽  
Robert A. Johnson
Keyword(s):  
Carbon Monoxide ◽  
Methyl Ester ◽  
Aminolevulinic Acid ◽  
No Synthase ◽  
Gracilis Muscle ◽  
Sprague Dawley ◽  
No Donor ◽  
First Order ◽  
No Formation ◽  
Sprague Dawley Rats

Vascular tissues express heme oxygenase, which metabolizes heme to form carbon monoxide (CO). CO promotes relaxation of vascular smooth muscle but also inhibits nitric oxide (NO) formation. This study examines the hypothesis that CO promotes endothelium- and NO synthase-dependent vasoconstriction of isolated arterioles. Studies were conducted on pressurized first-order gracilis muscle arterioles isolated from anesthetized male Sprague-Dawley rats. Exogenous CO, as well as a heme precursor, δ-aminolevulinic acid (δ-ALA), constricted arterioles with intact endothelium pretreated with phenylephrine; these effects were abolished by removal of the endothelium. CO- and δ-ALA-induced vasoconstrictions were converted to dilations by pretreatment with an inhibitor of NO synthase, Nω-nitro-l-arginine methyl ester, or with Nω-nitro-l-arginine methyl ester and an NO donor, sodium nitroprusside. Furthermore, CO-induced vasoconstriction was prevented by pretreatment with the NO synthase substrate l-arginine. This study shows that exogenous, as well as endogenously formed, CO can promote endothelium-dependent vasoconstriction in isolated gracilis muscle arterioles. Because CO-induced vasoconstriction is abolished by NO synthase blockade and by l-arginine, CO most likely promotes endothelium-dependent vasoconstriction by inhibiting endothelial NO formation.

scholarly journals Distinct Prominent Roles for Enzymes of Plasmodium berghei Heme Biosynthesis in Sporozoite and Liver Stage Maturation

2016 ◽  
Vol 84 (11) ◽  
pp. 3252-3262 ◽  
Author(s):  
Zaira Rizopoulos ◽  
Kai Matuschewski ◽  
Joana M. Haussig
Keyword(s):  
Life Cycle ◽  
De Novo ◽  
Aminolevulinic Acid ◽  
Vital Role ◽  
Heme Biosynthesis ◽  
Cycle Progression ◽  
Liver Stage ◽  
Content Type ◽  
Targeted Gene Deletion ◽  
Complex Regulation

Malarial parasites have evolved complex regulation of heme supply and disposal to adjust to heme-rich and -deprived host environments. In addition to its own pathway for heme biosynthesis,Plasmodiumlikely harbors mechanisms for heme scavenging from host erythrocytes. Elaborate compartmentalization ofde novoheme synthesis into three subcellular locations, including the vestigial plastid organelle, indicates critical roles in life cycle progression. In this study, we systematically profile the essentiality of heme biosynthesis by targeted gene deletion of enzymes in early steps of this pathway. We show that disruption of endogenous heme biosynthesis leads to a first detectable defect in oocyst maturation and sporogony in theAnophelesvector, whereas blood stage propagation, colonization of mosquito midguts, or initiation of oocyst development occurs indistinguishably from that of wild-type parasites. Although sporozoites are produced by parasites lacking an intact pathway for heme biosynthesis, they are absent from mosquito salivary glands, indicative of a vital role for heme biosynthesis only in sporozoite maturation. Rescue of the first defect in sporogony permitted analysis of potential roles in liver stages. We show that liver stage parasites benefit from but do not strictly depend upon their own aminolevulinic acid synthase and that they can scavenge aminolevulinic acid from the host environment. Together, our experimental genetics analysis ofPlasmodiumenzymes for heme biosynthesis exemplifies remarkable shifts between the use of endogenous and host resources during life cycle progression.

Effects of carbon monoxide and heme oxygenase inhibitors in cerebral vessels of rats and mice

2006 ◽  
Vol 291 (1) ◽  
pp. H223-H230 ◽  
Author(s):  
Jon J. Andresen ◽  
Nadeem I. Shafi ◽  
William Durante ◽  
Robert M. Bryan
Keyword(s):  
Carbon Monoxide ◽  
Heme Oxygenase ◽  
Control Mouse ◽  
Aminolevulinic Acid ◽  
Cerebral Arteries ◽  
Protoporphyrin Ix ◽  
Adult Rat ◽  
Nonspecific Effects ◽  
Middle Cerebral Arteries ◽  
Rats And Mice

Carbon monoxide (CO) has been postulated to be a signaling molecule in many tissues, including the vasculature. We examined vasomotor responses of adult rat and mouse cerebral arteries to both exogenously applied and endogenously produced CO. The diameter of isolated, pressurized, and perfused rat middle cerebral arteries (MCAs) was not altered by authentic CO (10−6 to 10−4 M). Mouse MCAs, however, dilated by 21 ± 10% at 10−4 M CO. Authentic nitric oxide (NO·, 10−10 to 10−7 M) dilated both rat and mouse MCAs. At 10−8 M NO·, rat vessels dilated by 84 ± 4%, and at 10−7 M NO·, mouse vessels dilated by 59 ± 9%. Stimulation of endogenous CO production through heme oxygenase (HO) with the heme precursor δ-aminolevulinic acid (10−10 to 10−4 M) did not dilate the MCAs of either species. The metalloporphyrin HO inhibitor chromium mesoporphyrin IX (CrMP) caused profound constriction of the rat MCA (44 ± 2% at 3 × 10−5 M). Importantly, this constriction was unaltered by exogenous CO (10−4 M) or CO plus 10−5 M biliverdine (both HO products). In contrast, exogenous CO (10−4 M) reversed CrMP-induced constriction in rat gracilis arterioles. Control mouse MCAs constricted by only 3 ± 1% in response to 10−5 M CrMP. Magnesium protoporphyrin IX (10−5 M), a weak HO inhibitor used to control for nonspecific effects of metalloporphyrins, also constricted the rat MCA to a similar extent as CrMP. We conclude that, at physiological concentrations, CO is not a dilator of adult rodent cerebral arteries and that metalloporphyrin HO inhibitors have nonspecific constrictor effects in rat cerebral arteries.

scholarly journals Heme Induction with Delta-Aminolevulinic Acid Stimulates an Increase in Water and Electrolyte Excretion

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Syed Quadri ◽  
Debra W. Jackson ◽  
Priyanka Prathipati ◽  
Courtney Dean ◽  
Keith E. Jackson
Keyword(s):  
Carbon Monoxide ◽  
Renal Function ◽  
Aminolevulinic Acid ◽  
Acute Administration ◽  
Bolus Administration ◽  
Sprague Dawley ◽  
Electrolyte Excretion ◽  
Sprague Dawley Rats ◽  
Before And After

Purpose. Studies were performed to examine hemodynamic and renal function before and after acute induction of the endogenous CO system with delta-aminolevulinic acid (DALA), which drives HO activity.Methods.In vivostudies were conducted on Inactin-anesthetized male Sprague Dawley rats (250–300 g) either with or without chronic pretreatment with L-NAME (50 mg/Kg, q12 hours x4d).Results. DALA (80 μmol/Kg, IV bolus) administration acutely increased endogenous CO production and HO-1 protein. In untreated and L-NAME-pretreated rats, DALA did not alter BP, GFR, or RBF but increased UF,UNaV, andUKV(untreated: Δ108.8 ± 0.28%, 172.1 ± 18.4%, and 165.2 ± 45.9%; pretreated: Δ109.4 ± 0.29%, 187.3 ± 26.9%, and 197.2 ± 45.7%). Acute administration of biliverdin (20 mg/kg, IV) and bilirubin (30 mg/kg, IV) to similarly treated animals did not alter UF,UNaV, andUKV.Conclusion. These results demonstrate that heme oxygenase induction increases urine and electrolyte excretion and suggest a direct tubular action of endogenous carbon monoxide.

Heme oxygenase activity in the adult rat aorta and liver as measured by carbon monoxide formation

1995 ◽  
Vol 73 (4) ◽  
pp. 515-518 ◽  
Author(s):  
Michael N. Cook ◽  
Kanji Nakatsu ◽  
Gerald S. Marks ◽  
Brian E. McLaughlin ◽  
Hendrik J. Vreman ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Heme Oxygenase ◽  
Rat Liver ◽  
Physiological Role ◽  
Rat Aorta ◽  
Supernatant Fraction ◽  
Smooth Muscle Relaxation ◽  
Aortic Tissue

Rat aorta was homogenized and the 13 000 × g supernatant fraction was tested for heme oxygenase (HO) activity by using a sensitive gas chromatographic method to measure carbon monoxide (CO), one of the products of the HO reaction. The rate of NADPH-dependent CO formation, an index of HO activity, was 1.41 ± 0.40 nmol CO∙mg−1 protein∙h−1 in the rat aorta supernatant fraction and 2.05 ± 0.55 nmol CO∙mg−1 protein∙h−1 in the rat liver 13 000 × g supernatant fraction, a tissue known to contain HO activity. Chromium mesoporphyrin (0.05 mM), an inhibitor of rat liver HO, significantly decreased HO activity by 26% in the aorta supernatant fraction and 50% in the liver supernatant fraction. On the basis of the results of this study, which demonstrated HO-catalyzed CO formation in aortic tissue, and previous observations that CO relaxes vascular smooth muscle, we suggest that a physiological role for CO in vascular smooth muscle relaxation should be further investigated.Key words: carbon monoxide, heme oxygenase, vascular smooth muscle, liver, gas chromatographic analysis.

Heme oxygenase-mediated endothelial dysfunction in DOCA-salt, but not in spontaneously hypertensive, rat arterioles

2004 ◽  
Vol 286 (5) ◽  
pp. H1681-H1687 ◽  
Author(s):  
Fruzsina K. Johnson ◽  
William Durante ◽  
Kelly J. Peyton ◽  
Robert A. Johnson
Keyword(s):  
Carbon Monoxide ◽  
Endothelial Dysfunction ◽  
Heme Oxygenase ◽  
Spontaneously Hypertensive Rat ◽  
Tap Water ◽  
Sprague Dawley ◽  
Hypertensive Rats ◽  
Spontaneously Hypertensive ◽  
Wistar Kyoto ◽  
Salt Sensitive Hypertension

Vascular heme oxygenase (HO) metabolizes heme to form carbon monoxide. Carbon monoxide inhibits nitric oxide synthase and promotes endothelium-dependent vasoconstriction. We reported HO-1-mediated endothelial dysfunction in Dahl salt-sensitive hypertension. Previous studies suggested that salt-sensitive hypertensive rats, but not spontaneously hypertensive rats (SHR), display endothelial dysfunction. This study examines the hypothesis that HO-1-mediated arteriolar endothelial dysfunction develops in deoxycorticosterone acetate (DOCA)-salt hypertensive (DOCA) rats, but not in SHR. Uninephrectomized (isoflurane anesthesia) male Sprague-Dawley rats received DOCA injections and saline drinking solution for 4 wk. Rats subjected to sham surgery received vehicle injections and tap water. Blood pressure was elevated in DOCA rats and SHR compared with sham and Wistar-Kyoto (WKY) groups. Aortic HO-1 expression and blood carboxyhemoglobin levels were elevated in the DOCA group, but not in SHR. In isolated gracilis muscle arterioles, ACh caused concentration-related vasodilation in all groups, with attenuated maximum responses in DOCA, but not in SHR, arterioles. Acute pretreatment with an inhibitor of HO, chromium mesoporphyrin, restored ACh-induced responses in DOCA arterioles to sham levels. ACh responses remained the same in SHR and WKY arterioles after chromium mesoporphyrin treatment. These data show that HO-1 levels and activity are increased and arteriolar responses to ACh are decreased in DOCA rats, but not in SHR. Furthermore, in DOCA arterioles, an inhibitor of HO restores ACh-induced vasodilation to sham levels. These results suggest that elevated HO-1 levels and activity, not resulting from hypertension per se, contribute to endothelial dysfunction in DOCA rats.

Potentiation of carbon monoxide-induced relaxation of rat aorta by YC-1 [3-(5'-hydroxymethyl-2'-furyl)-1-benzylindazole]

2000 ◽  
Vol 78 (4) ◽  
pp. 343-349 ◽  
Author(s):  
Brian E McLaughlin ◽  
Marc L Chretien ◽  
Christine Choi ◽  
James F Brien ◽  
Kanji Nakatsu ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Chromatographic Analysis ◽  
Saline Solution ◽  
Accurate Determination ◽  
Soluble Guanylyl Cyclase ◽  
Rat Aorta ◽  
Co Concentration ◽  
Endogenous Compound ◽  
Stimulation Of

The hypothesis that endogenous carbon monoxide (CO), produced during the oxidation of heme catalyzed by heme oxygenase (HO), plays a role similar to that of nitric oxide (NO) in the regulation of cardiovascular tone has been criticized because of the low potency of CO compared with NO in relaxing blood vessels and stimulating soluble guanylyl cyclase (sGC). This criticism has been muted by the demonstration that, in the presence of YC-1 [3-(5'-hydroxymethyl-2'-furyl)-1-benzylindazole], CO has similar potency to NO in stimulating sGC activity. In this study, we determined that YC-1 potentiated CO-induced relaxation of rat aortic strips (RtAS) by approximately ten-fold. Furthermore, CO-induced relaxation of RtAS was shown to be mediated through stimulation of sGC because vasorelaxation was inhibited by ODQ (1H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one), a selective sGC inhibitor, in the absence and presence of YC-1. A gas chromatographic-headspace method was used to measure CO concentration in Krebs' solution following the addition of CO-saturated saline solution to the tissue bath, in order to provide an accurate determination of RtAS exposure to CO. The tissue bath concentration of CO was shown to be approximately one-half of that calculated to be present. We conclude that should an endogenous compound exist with properties similar to that of YC-1, then the potency of CO as a vasorelaxant in the presence of this factor would be increased. As a consequence, CO could play a role in the regulation of cardiovascular tone, comparable to that of NO.Key words: carbon monoxide; YC-1 [3-(5'-hydroxymethyl-2'-furyl)-1-benzylindazole]; vasodilation; rat aorta; gas-chromatographic analysis.

An extracellular source of heme can induce a significant heme oxygenase mediated relaxation in the rat aorta

2002 ◽  
Vol 80 (8) ◽  
pp. 761-765 ◽  
Author(s):  
S Hosein ◽  
G S Marks ◽  
J F Brien ◽  
B E McLaughlin ◽  
K Nakatsu
Keyword(s):  
Carbon Monoxide ◽  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Blood Vessels ◽  
Vascular Smooth Muscle Cells ◽  
Heme Oxygenase ◽  
Muscle Cells ◽  
Rat Aorta ◽  
Bathing Medium

Carbon monoxide has been under active investigation for a role in controlling vascular tone throughout the last decade because of its ability to induce relaxation in blood vessels. The underlying mechanisms of this response are hypothesized to be mediated by soluble guanylyl cyclase (sGC) and, in some instances, KCa channels. The major source of CO in major blood vessels is the catabolic process of heme degradation, which is catalyzed by heme oxygenase (HO). This heme substrate could be derived from heme sources within vascular smooth muscle cells, such as heme proteins, or by uptake from the extracellular milieu. The current study shows that the isolated rat aorta relaxes upon exposure to pharmacological concentrations of heme in the bathing medium. This response was inhibited by an inhibitor of HO (tin protoporphyrin) and sGC (1-H-[1,2,4]-oxadiazolo[4,3-a]quinoxalin-1-one). These observations were interpreted to mean that vascular smooth muscle cells are capable of taking up and utilizing heme for the production of CO. Key words: carbon monoxide, heme oxygenase, heme, vascular smooth muscle.

scholarly journals Toxoplasma gondii requires its plant-like heme biosynthesis pathway for infection

2019 ◽  
Author(s):  
Amy Bergmann ◽  
Katherine Floyd ◽  
Melanie Key ◽  
Carly Dameron ◽  
Kerrick C. Rees ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
De Novo ◽  
Phylogenetic Analyses ◽  
Heme Biosynthesis ◽  
Microbial Pathogens ◽  
Biosynthesis Pathway ◽  
Prosthetic Group ◽  
Apicomplexan Parasites ◽  
Pathogenic Microbes ◽  
Living Organisms

Heme, an iron-enclosed organic ring, is essential for virtually all living organisms by serving as a prosthetic group in proteins that function in diverse cellular activities ranging from diatomic gas transport and detection to mitochondrial respiration to detoxification. Cellular heme levels in microbial pathogens can be a composite of endogenous de novo synthesis or exogenous uptake of heme or heme synthesis intermediates1,2. Intracellular pathogenic microbes switch routes for heme supply when heme availability in their replicative environment fluctuates through infections2. Here, we show that the Toxoplasma gondii, an obligate intracellular human pathogen, encodes a functional heme biosynthesis pathway. A chloroplast-derived organelle, termed apicoplast, is involved in the heme production. Genetic and chemical manipulation revealed that de novo heme production is essential for T. gondii intracellular growth and pathogenesis. Surprisingly, the herbicide oxadiazon significantly impaired Toxoplasma growth, consistent with phylogenetic analyses that show T. gondii protoporphyrinogen oxidase is more closely related to plants than mammals. We further improve upon this inhibition by 15-to 25-fold with two oxadiazon derivatives, providing therapeutic proof that Toxoplasma heme biosynthesis is a druggable target. As T. gondii has been used to model other apicomplexan parasites3, our study underscores the utility of targeting heme biosynthesis in other pathogenic apicomplexans.

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